Apparatus for controlling illumination range of vehicle lights

ABSTRACT

A light control system acquires presence information that indicates whether or not another vehicle is present in a lateral or rear direction relative to an own vehicle. If presence information indicates the presence of another vehicle, the illumination range of the headlights of the vehicle is changed so as to be narrower. Thus, when another vehicle enters the illumination range from a lateral direction relative to the vehicle equipped with the system, the illumination range of the lights of the vehicle is changed to a narrower range before the entry into the illumination range.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C.371 of International Application No. PCT/JP2013/064737 filed on May 28,2013 and published in Japanese as WO 2013/180111 A1 on Dec. 5, 2013.This application is based on and claims the benefit of priority fromJapanese Patent Application No. 2012-120963 filed May 28, 2012. Theentire disclosures of all of the above applications are incorporatedherein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an apparatus for controlling anillumination range of vehicle lights and a method thereof, and inparticular to an apparatus for controlling an illumination range of avehicle headlight and a method thereof.

2. Background Art

Various types of apparatus are known as vehicle light control apparatus.For example, in an apparatus disclosed in Patent Literature 1, a fieldof view ahead of the vehicle is picked up by a camera and it isdetermined whether or not another vehicle is present in the region ofthe field of view. Further, when the other vehicle is determined to bepresent, the illumination range of the headlights is changed so as to benarrowed.

Patent Literature 1 JP-A-2011-037342

However, the light control apparatus described in Patent Literature 1mentioned above still has a problem to be solved. For example, whenanother vehicle runs past the vehicle equipped with the light controlapparatus (hereinafter just referred to as the vehicle), such as whenthe vehicle is overtaken by the other vehicle, the problem arises.Specifically, when another vehicle runs past the vehicle and pulls infront of the vehicle (enters the illumination range of the headlights),the illumination range of the headlights is changed to a narrow rangeafter the other vehicle has actually pulled in front of the vehicle.Therefore, there is a delay in controlling the illumination range of theheadlights and thus the driver of the other vehicle may be dazzled.

SUMMARY

In light of such a problem, the light control apparatus that controlsthe illumination range of the headlights is also desired to suppress orprevent dazzling of the driver of another vehicle such as anothervehicle overtakes the vehicle and then enters the illumination range ofthe headlights.

In a light control apparatus related to a typical example, a vehicleinformation acquiring means acquires presence information that indicatesinformation as to whether or not another vehicle is present in a lateralor rear direction relative to the vehicle (equipped with the lightcontrol apparatus); and an illumination range changing means changes theillumination range of the headlights (hereinafter also simply referredto as “illumination range”) to a narrower range when presenceinformation indicating presence of the other vehicle is acquired.

According to the light control apparatus, the illumination range is madenarrower before the other vehicle enters the illumination rangesideways. Accordingly, the driver of the other vehicle is suppressed orprevented from being dazzled. It should be noted that the expression“when presence information indicating presence of the other vehicle isacquired” in the present disclosure includes “when presence informationis acquired” in which the information as to the presence of anothervehicle is absent, in a configuration in which presence information isacquired only when another vehicle is present in a lateral or reardirection relative to the vehicle equipped with the light controlapparatus.

For example, in the light control apparatus, the vehicle informationacquiring means also acquires relative travel directions of the vehicleequipped with the apparatus and the other vehicle, in addition to thepresence information; and the illumination range changing means changesthe illumination range of the headlights to a narrower range when theother vehicle is estimated to move into the illumination range, on thebasis of the relative travel direction.

According to the light control apparatus, the illumination range ischanged to a narrow range only when another vehicle moves into theillumination range. Therefore, unless another vehicle moves into theillumination range, a wider field of view can be ensured.

The problem set forth above can also be solved by a system or a programhaving the above configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a block diagram illustrating a schematic of a light controlsystem;

FIG. 2 is a flow chart illustrating an illumination control processperformed by an arithmetic section (CPU); and

FIG. 3 is a bird's eye view illustrating vehicles to explain a specificexample in calculating a moving time period.

DESCRIPTION OF EMBODIMENTS

With reference to the drawings, hereinafter is described a light controlsystem implementing an apparatus and a method related to an embodimentof the resent invention.

FIG. 1 shows a schematic of a light control system 1. As shown in thefigure, the light control system 1 is mounted to a vehicle, such as apassenger car, and has a function of changing an illumination range ofthe headlights of the vehicle. Specifically, as shown in FIG. 1, thelight control system 1 includes an arithmetic section 10, camera 21,radar device 22, steering angle sensor 24, vehicle speed sensor 25 andlight control section 30.

It should be noted that the vehicle equipped with the light controlsystem 1 related to the present embodiment is referred to as the ownvehicle, i.e., the system-equipped vehicle, as necessary, fordistinction from another (or different) vehicle.

The camera 21 is arranged so that its imaging range includes at least anillumination range of the headlights in the travel direction of thevehicle (ahead of the vehicle in particular). The camera 21 isconfigured as a color camera that picks up an image in color in thefield of view of the imaging range. The camera 21 transmits a picked-upimage to the arithmetic section 10.

The radar device 22 is configured as a well-known radar device having afunction of radiating laser beams, or electromagnetic waves, such asradio waves, or sonic waves and detecting the reflected waves to detecta distance to an object that has reflected the electromagnetic waves orthe sonic waves and a position of the object. The radar device 22 isarranged at each of corner portions in the right-rear and left-rearsections of the vehicle, and emits electromagnetic waves or sonic wavesso that a targeted detection region is created in the lateral and reardirections relative to the vehicle. Then, the radar device 22 transmitsa detection result of an object to the arithmetic section 10.

The steering sensor 24 is configured as a well-known steering anglesensor that detects a steering angle of a vehicle. The vehicle speedsensor 25 is configured as a well-known vehicle sensor that detects atravel speed of a vehicle.

The light control section 30 controls the optical axes of the headlightsupon reception of a detection result of vehicle light. Specifically,upon reception of a detection result that vehicle light is present in apicked-up image, the light control section 30 switches the headlights tolow beam, and upon reception of a detection result that no vehicle lightis present in a picked-up image, the light control section 30 switchesthe headlights to high beam. It should be noted that the light controlsection 30 may have a configuration in which the optical axes are movedto a direction where no other vehicle is present (e.g., downward orleftward) according to an instruction from the arithmetic section 10.

The arithmetic section 10 is configured as a well-known microcomputerthat includes a CPU 11 and a memory 12, such as ROM (serving as anon-transitory computer readable medium) and RAM. The arithmetic section10 performs various processes, such as an illumination control processdiscussed later, on the basis of programs (including a light controlprogram) stored in the memory 12. The memory 12 stores parameters thatindicate characteristics of vehicle light (including values correlatedto the parameters of positions, such as size, color and height, anddistances between paired lights and behaviors thereof), and parametersthat indicate characteristics of light sources other than vehicles. Itshould be noted that the parameters stored in the memory 12 are used indetecting the light sources indicating vehicle light from a picked-upimage, being distinguished from the light sources other than vehiclelight.

The arithmetic section 10 (CPU 11) detects another vehicle which ispresent around the own vehicle. When there is a probability that thedriver of the other vehicle is dazzled, the CPU 11 repeatedly performs,at predetermined intervals, the illumination control process fornarrowing the illumination range of the headlights (switching theheadlights to low beam). As shown in FIG. 2, in the illumination controlprocess, a picked-up image is firstly acquired by the camera 21 (stepS110).

Subsequently, the CPU 11 acquires, from the radar device 22, informationon an object (position and distance) detected by the radar device 22(step S120). At the same time, the CPU 11 acquires information on theown vehicle that is equipped with the light control system 1 (stepS130). The information on the own vehicle corresponds such as to asteering angle detected by the steering sensor 24, and a vehicle speeddetected by the vehicle speed sensor 25.

Then, the CPU 11 detects information of another vehicle which is presentin the lateral and rear directions relative to the own vehicle (stepS140). Specifically, the CPU 11 detects the shape of an object detectedby the radar device 22 (detects what can be estimated from a collectionof pieces of position information) and records the detection in thememory 12 as another vehicle. It should be noted that another vehicledetected in the previous and the further preceding cycles, even if theother vehicle is not detected in the present-time process, is recordedin the memory 12 as having moved according to a relative motion vectorand regarded to have been detected.

In this process, when an object can be estimated as being a vehicle onthe basis such as of the shape and size, the CPU 11 specifies thepositions corresponding to dazzling objects from among the portions ofthe other object. The dazzling objects each indicate a portion of theother vehicle by which the driver of the other vehicle, when it hasentered the illumination range, is likely to be dazzled. The positionsof the dazzling objects include, for example, those of sideview mirrors,a rearview mirror and a rear window (the window in the rear of thevehicle). When the positions of the dazzling objects cannot be specifiedfrom the shapes and the like, the positions where the dazzling objectsare arranged in generally-used vehicles are recorded on the memory 12 asthe positions of the dazzling objects of the other vehicle, withreference to the location of the other vehicle.

Then, the CPU 11 processes the picked-up image to determine whether ornot another vehicle is present ahead of the own vehicle (step S150). Atthis step, the CPU 11 makes use of a well-known image processingtechnique of extracting light sources from a picked-up image anddetecting vehicle light from the light sources to thereby determinewhether or not another vehicle is present in the picked-up image. Inmaking the determination, the CPU 11 uses the parameters stored in thememory 12, which indicate the characteristics of vehicle light, or theparameters which indicate the characteristics of the light sources otherthan those of vehicles.

If another vehicle is present in a forward direction (YES at step S150),the CPU 11 sends an output to the light control section 30 (step S210).The output indicates that the illumination range of the headlightsshould be switched to anti-glare light distribution (light distributionof low beam) which is narrower than the normal illumination range(normal light distribution of high beam). Then, the illumination controlprocess is terminated.

If no different vehicle is present in a forward direction (NO at stepS150), the CPU 11 determines whether or not another vehicle is presentin a lateral or rear direction (step S160). If no different vehicle ispresent in the lateral or rear direction (NO at step S160), the CPU 11sends an output to the light control section 30, the output indicatingthat the illumination range should be switched to the normal lightdistribution (step S200). Then, the illumination control process isterminated.

If another vehicle is present in the lateral or rear direction (YES atstep S160), the CPU 11 calculates a relative motion vector (step S170).Specifically, the CPU 11 tracks, in a time-series manner, theinformation on the shape and position of an object detected by the radardevice 22 to detect a relative motion vector (presence/absenceinformation, position of presence, relative travel direction andrelative speed) that is a motion vector for an object as a vehicle whichis estimated to be another vehicle, and records the relative motionvector on the memory 12. However, steps S170 and S180 only have to beperformed for different vehicles which are detected by the radar device22 in the present-time process.

Then, the CPU 11 calculates time that will be taken before the driver ofthe other vehicle located in the lateral or rear direction relative tothe own vehicle is dazzled by the headlights of the own vehicle (stepS180). While the illumination range of the headlights in the normallight distribution is recorded in advance on the memory 12, the CPU 11calculates, at this step, the time (moving time period) taken for theother vehicle (any one of the dazzling objects in particular) to enterthe illumination range when the other vehicle moves along the relativemotion vector mentioned above.

For example, let us assume a situation, as shown in FIG. 3, where theown vehicle A equipped with the light control system 1 travels on theleft lane of a three-lane road, and another vehicle B traveling on thecenter line and another vehicle C traveling on the right lane run pastthe vehicle A. In this situation, the distance to an entry point intothe illumination range (the hatched range inside the broken line) islonger for the other vehicle C than for the other vehicle B. This isbecause the distance from the vehicle A to the other vehicle C is largerthan that to the other vehicle B in the lateral direction relative tothe vehicle A, i.e., perpendicular to the travel direction of thevehicle A.

Accordingly, moving time periods set at the present step (step S180)depend on the positions of the other vehicles (in the lateraldirections), although the relative travel speeds are the same.Specifically, a longer moving time period is set as the lateral distancefrom the own vehicle to another vehicle becomes larger (the same appliesto a wait time period discussed later).

Then, it is determined whether or not the timing has come at which thedriver of another vehicle is dazzled (step S190). At this step, the CPU11 sets, first, the wait time period with a value equal to or slightlysmaller than the time taken for the other vehicle to enter theillumination range. Then, the CPU 11 determines, for each of the othervehicles recorded on the memory 12, whether or not the wait time periodhas elapsed since step S180 has been performed last.

If the timing has come at which the driver of another vehicle is dazzled(YES at step S190), control proceeds to step S210 mentioned above. Onthe other hand, if the timing has not come (NO at step S190), controltransfers to step S200 mentioned above.

In the light control system 1 described in detail in the above, thearithmetic section 10 acquires the presence information that indicateswhether or not another vehicle is present in the lateral or reardirection relative to the own vehicle (steps S120, S140 and S170). Ifthe presence information indicating the presence of another vehicle isacquired, the illumination range of the headlights is changed to anarrower range (steps S160 to S210).

According to the light control system 1, the illumination range iscontrolled to a narrower range prior to the entry of another vehicleinto the illumination range from the lateral direction relative to theown vehicle. Thus, the driver of the other vehicle is prevented orsuppressed from being dazzled. Further, in the light control system 1,the arithmetic section 10 acquires not only the presence information butalso relative travel directions of another vehicle and the own vehicle.Then, if the entry of the other vehicle into the illumination range isestimated from the relative travel direction (if the relative traveldirection of the other vehicle coincides with the direction of theillumination range), the illumination range of the headlights is changedto a narrower range.

According to the light control system 1, the illumination range iscontrolled to a narrower range only when another vehicle moves into theillumination range. Accordingly, unless another vehicle moves into theillumination range, a wider field of view is ensured.

Further, in the light control system 1, the arithmetic section 10acquires not only the presence information but also a relative motionvector of another vehicle with respect to the own vehicle, followed byestimating a moving time period for the other vehicle to enter theillumination range, on the basis of the relative motion vector. Then, await time period is set using the moving time period as being an upperlimit. Then, after lapse of the wait time period, the illumination rangeof the headlights is changed to a narrower range. The start point formeasuring the wait time period is set, for example, to a point when therelative motion vector is acquired or when the moving time period isestimated. In calculating the wait time period, the arithmetic section10 acquires a distance to another vehicle in a lateral direction(lateral distance) that is perpendicular to the travel direction of theown vehicle, and makes the wait time period longer as the lateraldistance becomes larger.

According to the light control system 1, the illumination range isprevented from being narrowed as much as possible, unless the driver ofanother vehicle is dazzled. Thus, in such a situation, a wider field ofview can be ensured.

Further, in the light control system 1, the arithmetic section 10 alsoacquires the positions of the dazzling objects (sideview mirrors, arearview mirror and a rear window (the window in the rear of thevehicle)) from among portions of another object. The dazzling objectseach indicate a portion by which the driver of the other vehicle, whenit has entered the illumination range, is likely to be dazzled. Then,the arithmetic section 10 estimates the moving time period thatindicates time before a dazzling object of the other vehicle enters theillumination range.

According to the light control system 1, the time taken for the ownvehicle to dazzle the driver of another vehicle can be correctlydetected.

Other Embodiments

The present invention should not be construed as being limited to theforegoing embodiment, but may have various modes as far as the modes arein the technical scope of the present invention.

For example, the foregoing embodiment is configured to detect a relativemotion vector (present location, relative travel direction and relativespeed) of another vehicle located in the lateral or rear directionrelative to the own vehicle, using the radar device 22. Alternatively,in another configuration, the camera 21 may be arranged being orientedto the rear or lateral direction relative to the own vehicle and arelative motion vector of another vehicle may be detected from apicked-up image. Alternatively, information regarding a (absolute)motion vector of another vehicle may be received usingvehicle-to-vehicle communication, for example, and a difference from themotion vector of the own vehicle may be calculated to thereby calculatea relative motion vector.

Further, in the foregoing embodiment, the illumination range of theheadlights is ensured to be changed after lapse of the wait time period.Alternative to this, the illumination range may be immediately changedat the time point when another vehicle is detected in the rear orlateral direction, without providing the wait time period. Further, inthe foregoing embodiment, the illumination range is change according tothe relative motion vector. Alternatively, the illumination range may bechanged according to a relative travel speed or a relative traveldirection instead of the relative motion vector.

In the illumination control process of the present embodiment, stepsS120, S140 and S170 correspond to the vehicle information acquiringmeans, while steps S160 to S210 correspond to the illumination rangechanging means.

REFERENCE SIGNS LIST

-   1 . . . Light control system,-   10 . . . Arithmetic section,-   12 . . . Memory,-   21 . . . Camera,-   22 . . . Radar device,-   24 . . . Steering angle sensor,-   25 . . . Vehicle speed sensor, and-   30 . . . Light control section.

What is claimed is:
 1. An apparatus that is mounted to a vehicle andcontrols an illumination range of headlights of the vehicle, theapparatus comprising: acquiring means for acquiring presence informationthat indicates information as to whether or not another vehicle ispresent in a lateral or rear direction relative to the vehicle; andchanging means for changing the illumination range of the headlights toa narrower range when the acquiring means acquire presence informationindicating presence of the other vehicle, wherein the acquiring means isconfigured to acquire a relative motion vector indicating relativetravel directions between the other vehicle and the vehicle, in additionto the presence information, and the changing means i) estimate a movingtime period that indicates time taken for the other vehicle to enter theillumination range, on the basis of the relative motion vector, themoving time period depending on where the other vehicle is present inthe lateral or rear direction, and ii) change the illumination range ofthe headlights to a narrower range after lapse of a wait time periodthat is set with the moving time period as being an upper limit. 2.(canceled)
 3. (canceled)
 4. The apparatus according to claim 1, wherein:the acquiring means is configured to also acquire dazzling objects fromamong portions of the other vehicle, the dazzling objects each being aportion having a probability of dazzling the driver of the other vehiclewhen the other vehicle has entered the illumination range; and thechanging means is configured to estimate a moving time period thatindicates time taken for each of the dazzling objects of the othervehicle to enter the illumination range.
 5. (canceled)
 6. (canceled) 7.A light control program that allows a non-transitory computer readablemedium to function as each of the means that configure the apparatusrecited in claim
 1. 8. A method for controlling an illumination range ofheadlights of a vehicle, the method comprising: acquiring i) presenceinformation that indicates information as to whether or not anothervehicle is present in a lateral or rear direction relative to thevehicle and ii) a relative motion vector indicating relative traveldirections between the other vehicle and the vehicle; estimating amoving time period that indicates time taken for the other vehicle toenter the illumination range, on the basis of the relative motionvector, when the presence information is acquired, the moving timeperiod depending on where the other vehicle is present in the lateral orrear direction; and presence information is acquired, the moving timeperiod depending on where the other vehicle is present in the lateral orrear direction; and changing the illumination range of the headlights toa narrower range after lapse of a wait time period that is set with themoving time period as being an upper limit.